Thread (20 messages) 20 messages, 3 authors, 2020-02-06

Re: [PATCH 1/3] ARM: exynos_defconfig: Enable SCHED_MC

From: Krzysztof Kozlowski <krzk@kernel.org>
Date: 2020-01-31 12:47:54
Also in: linux-devicetree, linux-pm, linux-samsung-soc, lkml

On Mon, 27 Jan 2020 at 22:55, [off-list ref] wrote:
From: Lukasz Luba <lukasz.luba@arm.com>

Since the 'capacities-dmips-mhz' are present in the CPU nodes, make use of
this knowledge in smarter decisions during scheduling.

The values in 'capacities-dmips-mhz' are normilized, this means that i.e.
when CPU0's capacities-dmips-mhz=100 and CPU1's 'capacities-dmips-mhz'=50,
cpu0 is twice fast as CPU1, at the same frequency. The proper hirarchy
in sched_domain topology could exploit the SoC architecture advantages
like big.LITTLE.
I do not quite get how this is related to rationale behind changing defconfig...
Enabling the SCHED_MC will create two levels in
sched_domain hierarchy, which might be observed in:
This is looks more convincing... but still what is the need? To work with EAS?
grep . /proc/sys/kernel/sched_domain/cpu*/domain*/{name,flags}
/proc/sys/kernel/sched_domain/cpu0/domain0/name:MC
/proc/sys/kernel/sched_domain/cpu0/domain1/name:DIE
...
/proc/sys/kernel/sched_domain/cpu0/domain0/flags:575
/proc/sys/kernel/sched_domain/cpu0/domain1/flags:4223
Not related to defconfig change and not visible after this commit.

Best regards,
Krzysztof
quoted hunk ↗ jump to hunk
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 arch/arm/configs/exynos_defconfig | 1 +
 1 file changed, 1 insertion(+)
diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
index e7e4bb5ad8d5..1db857056992 100644
--- a/arch/arm/configs/exynos_defconfig
+++ b/arch/arm/configs/exynos_defconfig
@@ -8,6 +8,7 @@ CONFIG_PERF_EVENTS=y
 CONFIG_ARCH_EXYNOS=y
 CONFIG_CPU_ICACHE_MISMATCH_WORKAROUND=y
 CONFIG_SMP=y
+CONFIG_SCHED_MC=y
 CONFIG_BIG_LITTLE=y
 CONFIG_NR_CPUS=8
 CONFIG_HIGHMEM=y
--
2.17.1
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